British Home Secretary Amber Rudd said whoever is behind the attack is guilty of a "brazen and reckless act".
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About 180 military personnel have also been called upon by the police to remove evidence in Salisbury potentially contaminated by a deadly nerve agent. The expert advice is that there is no evidence to suggest a wider public health risk at this time.
Mr Sutyagin told Radio Svoboda that when he met him, Mr Skripal seemed to be a nice, calm and normal man who did not seem the type to take drugs.
Skripal and Yulia remain in a serious condition along with a police officer who came in contact with the same substance.
Ms Rudd was seen at the bench where Mr Skripal and his daughter collapsed in the city centre, which remains cordoned off by police.
The attempted murder of Mr Skripal has drawn comparisons to the 2006 assassination of Alexander Litvinenko, who ingested the rare and highly radioactive Polonium 210 in London.
Police found Skripal, 66, and Yulia, 33, unconscious on a bench outside The Maltings shopping center in Salisbury.
"These nerve agents are typically very hard to make, except for experienced chemists with a considerable level of safety and handling precautions", says Chris Morris, a medical toxicologist at Newcastle University.
Indeed, chemical weapons labs across the world probably synthesized hundreds of organophosphorus agents over the decades, most of which were never selected for military use.
Numerous military personnel will be working behind the scenes and helping the police with relatively straightforward tasks, such as securing sites and removing objects, including ambulances, for decontamination.
Firefighters, police officers and ambulance crews in regular uniforms stood nearby in Salisbury's London Road cemetery.
He is believed to have been the first person at the scene, although there are now suggestions he may have become ill after retracing Mr Skripal's steps from his home in Salisbury.
Police have cordoned off sites including ex-spy Sergei Skripal's house, a vehicle, the cemetery where his wife is buried, a restaurant and a pub.
Skripal, a retired Russian military intelligence colonel, was one of four prisoners released by Moscow in 2010 in exchange for 10 Russian sleeper agents in the United States, as part of a swap which included high-profile spy Anna Chapman.
Valery Morozov, another former Russian intelligence officer who now lives in exile in Britain, said Skripal was still working with Russian military intelligence, Polygraph reported.
He told Associated Press: "There are lots of former security officers that deserted to the West". It's nearly like an act of war.
No details on which nerve agent was used have been given.
The UK is preparing retaliatory measures if it's shown that Russian Federation was responsible for the attack on Skripal who had settled in Salisbury, southern England after a spy swap in 2010.
Those branded enemies of the Russian state have sometimes died mysteriously overseas, and the Skripal case echoes the death of Alexander Litvinenko, a former Russian agent who was poisoned in London in 2006 with radioactive polonium-210.
"But in order to conduct such cases, it is necessary not to immediately run out on TV screens with unfounded allegations", Lavrov was quoted as saying by Russian state news agency Tass in the Ethiopian capital, Addis Ababa.
There has been speculation that the Russian state, even though it completed the destruction of its declared chemical weapons stockpile a year ago, could still be behind the attack - a suggestion dismissed by Moscow.